1. Field of the Invention
The present invention relates to an information recording and reproducing method for recording information on an information recording medium using a semiconductor laser and an information reproducing apparatus for executing the method.
2. Description of Related Art
The kind of an optical disk is versatile as an information recording medium capable of recording information using light. For example, as an optical disk capable of writing information only once, there have been known CD-R, DVD-R, R+ and BD (Blu-ray Disc)-R. In addition, as an optical disk capable of writing information multiple times, erasing and rewriting written information, there have also been known CD-RW, DVD-RAM, DVD-RW, +RW and BD-RE.
Each optical disk being a recording medium disperses in thickness of a cover layer, thickness of a recording film and sensitivity. If conditions for recording data are fixed, an optimum reproduced signal cannot be obtained due to manufacturing tolerances of the optical disk. Similarly, in the recording and reproducing apparatus, influence cannot be ignored that aberration is generated in an optical pickup system by manufacturing tolerances of various components and adjusting tolerances of components such as deviation in focus target value.
An optical disk recording and reproducing apparatus optimizes recording conditions for providing an optical disk with a recording power and a recording pulse at the time of recording information in the optical disk in consideration of such tolerances to stably record and reproduce information (refer to, for example, Japanese Patent Laid-Open No. 2006-12226).
An information recording and reproducing apparatus has determined conditions for recording information on an optical disk to optimize a reproduced signal in such a manner that a recording mark is written on trial in a predetermined area of the optical disk and data is reproduced from the recording mark written on trial.
As one of indexes for evaluating whether a reproduced signal is optimal, there is available a parameter which a reproduced signal has with respect to a time base. As this parameter, there is a jitter as displacement which the reproduced signal has with respect to a reference clock. The information recording and reproducing apparatus forms the recording mark to minimize the jitter.
[Patent Document 1] Japanese Patent Laid-Open No 2006-12226
When data is recorded at a high speed on the optical disk, the information recording and reproducing apparatus cannot detect an evaluation parameter from the reproduced signal on the time base, which makes it difficult to optimize the recording signal. Particularly in the sextuple-speed (6×) recording on BD, the transmission band is as broad as 100 MHz, which makes it more difficult that the information recording and reproducing apparatus detects the evaluation parameter. As a result, a problem is raised in that the shift adjustment of the recording pulse cannot stably be performed at the time of recording information on the optical disk at a high speed.